Method of molding replica wooden beams

ABSTRACT

A mold box containing a wooden beam pattern on the bottom portion thereof is provided. An elastomer is cast in the box containing the pattern and cured therein to form an elastomeric mold having the surface configurations of the wooden beam on its inner surfaces. The elastomeric mold is then removed from the mold box and placed in a form to rigidify it. A foamable low density rigid urethane foam resin reaction mixture is then cast into the elastomeric mold and the mold closed by a cover having a depending core member. The reaction mixture is permitted to foam and cure and then the product a replica beam is removed from the mold. The skin is removed from a portion of the replica beam to aid in mounting the beam. A wood stain is applied to the replica beam and the stained surface is burnished while the stain is still wet.

April 9, 1974 s. H. BASSETT 3,303,277

METHOD OF MOLDING REPLICA WOODEN BEAMS Original Filed Aug. 16, 1968 3SheetsSheet 1 VIII/7151111111 I F G. 2

I I INVENTOR. 40 8TP///V H. ansserr ////A BY ATTORNE S April 9, 1974 s.H. BASSETT 3,803,277

METHOD 0F MOLDING REPLICA WOODEN BEAMS Original Filed Aug. 16, 1968 5Sheets-Sheet 2 INVENTOR. STEPHEN fl. BASSETT Z ATTORNEY? S. H. BASSETTMETHOD OF MOLDING REPLICA WOODEN BEAMS April 9, 1974 3 Sheets-Sheet 5Griginal Filed Aug. 16 1968 INVENTOR. sum/4w BASSETT AT ORN S UnitedStates Patent 3,803,277 METHOD OF MOLDING REPLICA WOODEN BEAMS StephenH. Bassett, 20 Wellington Drive, New York, N.Y. 07724 Originalapplication Aug. 16, 1968, Ser. No. 753,117, now Patent No. 3,561,181,dated Feb. 9, 1971. Divided and this application Feb. 9, 1970, Ser. No.14,697

Int. Cl. B29d 27/04; B4411 5/00 US. Cl. 264-48 3 Claims ABSTRACT OF THEDISCLOSURE A mold box containing a wooden beam pattern on the bottomportion thereof is provided. An elastomer is cast in the box containingthe pattern and cured therein to form an elastomeric mold having thesurface configurations of the wooden beam on its inner surfaces. Theelastomeric mold is then removed from the mold box and placed in a formto rigidify it. A foama-ble low density rigid urethane foam resinreaction mixture is then cast into the elastomeric mold and the moldclosed by a cover having a depending core member. The reaction mixtureis permitted to foam and cure and then the product a replica beam isremoved from the mold. The skin is removed from a portion of the replicabeam to aid in mounting the beam. A wood stain is applied to the replica beam and the stained surface is burnished while the stain is stillwet.

This application is a divisional application of applicants earlier filedcopending patent application, Ser. No. 753,117, filed Aug. 16, 1968, andentitled Replica Wooden Beams (now US. Pat. No. 3,561,181).

This invention relates generally to molding plastic articles, such asreplica wooden beams and panels.

Wood, and particularly properly finished hardwood, has long beenconsidered to be an exceedingly attractive and luxurious material forhome and commercial furnishing and decorating. Yet further, and withrecent increases in the cost of and decreases in the availability ofskilled craftmanship, and recent revival of colonial architecturalstyles have created a need for the development of replica handhewn andhandcarved wooden articles which embody the appearance of the originalarticle and which are yet capable of mass production, utilizingrelatively unskilled or semiskilled labor, at more reasonable costs; andwhich may be readily and easily utilized as decorative materials.

Various plastic and other materials have been suggested as substitutesfor the relatively expensive handcarved and handhewn hardwood articlesso much in current demand. However, such substitutes as have heretoforebeen suggested have not been entirely satisfactory, either beinginferior in appearance to the original article, difiicult to install, oftoo high a cost, too easily damaged, or too difiicult to repair ifdamaged.

Accordingly, it is a primary object of the present invention to moldreplica wooden articles, and particularly of handcarved or handhewnwooden articles, which accurately reproduce the optical, tactile andacoustic characteristics of the genuine article.

Another primary object of the present invention, in addition to theforegoing object, is the molding of such replica articles which may bereadily and easily handled, utilized and installed, which are not easilydamaged and which may be readily and easily repaired if damaged.

Yet another primary object of the present invention, in addition to eachof the foregoing objects, is the molding of such replica articles whichare light in weight, fire resistant, capable of being cut with ordinarywoodworking 3,803,277 Patented Apr. 9, 1974 Ice tools and susceptible tobeing readily adhesively mounted.

Yet still another primary object of the present invention, in additionto each of the foregoing objects, is the provision of methods for makingmolds.

The invention resides in the combination, construction, arrangement anddisposition of the various component parts and elements incorporated inmolding the articles. The present invention will be better understood,and objects and important features other than those specificallyenumerated above, will become apparent when consideration is given tothe following details and description, which when taken in conjunctionwith the annexed drawing, describes, discloses, illustrates and showscertain preferred embodiments or modifications of the present inventionand what is presently considered and believed to be the best mode ofpracticing the principles thereof. Other embodiments or modificationsmay be suggested to those having the benefit of the teachings herein,and such other embodiments or modifications are intended to be reservedespecially as they fall within the scope and spirit of the subjoinedclaims.

In the drawing:

FIGS. 1-10 are each isometric, partial cross-sectional viewsillustrating, in sequence, steps in the practice of the presentinvention and apparatus thereof;

FIG. 11 is an isometric pictorial view illustrating steps and apparatusfor practicing the present invention in acctgrdange with anotherembodiment or modification there- 0 an FIG. 12 is a cross-sectional viewtaken along line 12-12 of FIG. 11.

With reference now to the drawing, and particularly to FIGS. 110thereof, there is shown and illustrated therein a sequence of steps andapparatus which may be utilized for the production of articles inaccordance with the present invention and exemplified by the productionof replica handhewn wooden beams. Generally, in accordance with thepresent invention, a mold is fabricated of, for example, a urethaneelastomer, utilizing a handhewn wooden beam as a pattern. A foamedplastic material, such as foamed urethane, is then formed in such mold,and then stained and otherwise finished in accordance with the presentinvention to produce replicas of the handhewn pattern which are ofexceptional realism but which may be produced at a much lower cost.

A pattern, such as a handhewn wooden beam 20' of which replicas are tobe formed may, in accordance with the present invention be secured to agenerally rectangular pattern board 22 in any convenient fashion, as bymeans of nails, screws, adhesives, or the like, generally centrallythereof so as to leave a marginal portion of the pattern board generallyunobstructed. A mold box 24 comprising, for example, end boards 26 andside boards 28 structurally associated with one another in generallyright angle configuration may then be positioned in generally upstandingrelationship to the pattern board 22 and in spaced apart relationship tothe pattern 20 so as, together with the pattern board 22 to form areceptacle having a generally open and unobstructed top with the pattern20 being disposed generally centrally within the receptacle. The moldbox 24 and the pattern board 22 may be secured together, in anyconvenient manner. For example, the pattern board 22 and the mold box 24may be provided with fastening means, such as hook members 30structurally associated with the side boards 28 and latching bars 32pivotally associated with the pattern board 22. The hook members 30 may,for example, be secured with the side boards 28, as by means of screws34 in pairs on opposite sides of the mold box 24 and projectingoutwardly thereof a distance slightly greater than the thick ness of thepatternboard 22 and provided with oppositely facing notches 36 adaptedto be engaged by the latching bars 32 and spaced from the side boards 28a distance substantially equal to the thickness of the pattern board 22.The latching bars 32 may be pivotally associated with the pattern board22 in any convenient manner, as by each latching bar 32 being securedthereto by a pivot screw 38.

The mold box 24 may then be filled with an appropriate mold material.For example, a urethane casting elastomer which will cure toapproximately 50-60 Shore A Durometer hardness.

Since urethane elastomers react with water to generate carbon dioxidegas, the usual procedures utilized to handle such materials require thatextensive precautions be utilized to maintain the material free ofcontact with water or moisture if an unblemished surface is to beproduced. Without such precautions, the surface will generally be, atleast to some extent, pockmarked. In the present usage, it isexceedingly important that the surface of the elastomer adjacent thepattern 20 be free of any pockmarking. Additionally, accurate moldformation requires that the elastomer be in intimate contact with thepattern 20.

While it has been generally recognized that contact with moisture willproduce carbon dioxide gas and the attendant bubbling, prior efforts toprevent such bubbling have been directed towards elimination of moistureto prevent the formation of carbon dioxide bubbles. However, it has notbeen previously recognized that it is not the presence of water thatcreates flaws in the cured material but, rather, the presence of thebubbles which causes the flaws. Accordingly, it is not necessary tocompletely eliminate moisture, provided that the usual efiects ofmoisture presence, namely bubbling are eliminated. Accordingly, curingthe elastomer mold 40 under heat and pressure, as in a pressure vesselor autoclave 42 retains the elastomer in intimate contact with thepattern 20 and prevents the formation of carbon dioxide bubbles.

As an aid in positioning the mold box within the autoclave or pressurevessel 42, a plurality of rollers 44 may be provided therein forsupporting the pattern board 22 and hot dry air, for example atapproximately 250 F. and 60 lbs. per square inch pressure may bemaintained within the autoclave 42, as through an air inlet 46, asillustrated diagrammatically in FIG. 2.

Following curing of the mold 40 within the autoclave 42, the pattern 20and pattern board 22 may be removed, to leave a mold cavity 48 in themold 40, with the walls of the mold 40 being, for example, /z" thick. Byapplication of a release compound to the pattern 20 and the patternboard 22, they may be readily removed from contact with the mold 40. Ifno release compound is utilized on the mold box 24, the mold 40 will besecurely bonded thereto.

A mold board 48 may then be fitted to the mold box 24 adjacent thebottom of the mold 40 and secured with the end boards 26 and side boards28 in any convenient manner, as by means of glue, nails, screws, and thelike. The mold board 48 may be provided with one or more air fittings 50for use in ejecting the finished articles from the mold, as will bedescribed in more detail hereinafter.

If desired, the mold 40 may be fabricated of other materials, such assilicones and may be impregnated with materials, such as oil, as an aidin releasing finished articles from the mold.

The completed molds may then be utilized for the molding of replicas ofthe pattern, such as replica wooden beams from a material, such asurethane resin foam. For a number of reasons, which will become apparenthereafter, it has been found preferable to utilize a resin system havinga relatively high viscosity, short rise time, short cream time, andrapid gelation time. For example, General Latex foam system No. RUR141-30, which has a free density of approximately 4 lbs. per cubic foot;a cream time of approximately 60 seconds, a rise time of approximately180 seconds, a viscosity approximately within the range of l,0002,000centipoise; exhibits poor horizontal movement and poor flowability hasbeen found to be particularly suited for the production of replicawooden beams in accordance with the present invention. It is to beexpressly understood, however, that many other systems are suitable foruse in the present invention having, for example, a free rise density of2-6 lbs. per cubic foot.

The mold may be moved under a nozzle, as indicated by FIG. 5, and filledpart-way with the urethane resin. It has been found advisable that theslightly greater quantity of resin be utilized than that necessary tofill the cavity and, for example, a quantity sufficient to result in afinal density averaging approximately 8 lbs. per cubic foot has beenfound to work satisfactorily. The poor fiowability and high viscosityaid in attaining a proper distribution of resin within the elongatedcavity. After the resin 52 has been deposited in the mold cavity, acover 54 having secured thereto a core member 56 may be aflixed to themold box 24, as illustrated in FIG. 5. The core member 56 may bestructurally associated with the cover 54 in any convenient manner, asby means of adhesives, nails, screws, or the like; may be fabricated,from example, of wood; and may be of such height and thickness as toleave a space of approximately lMt-P/z" within the mold 40 for the resin52. The interior of the cover 54 and the core member 56 may be coveredor coated, to aid in release thereof from the resin 52. The cover 54 maybe provided with matching bars 32 as was the pattern board 22 forcooperating with the hook members 30.

If the proper resin selection is made, as set forth hereinabove, it isnot necessary for the hook members 30 and latching bars 32 to tightly orsealingly hold the cover 54 on the mold box 24. It is sufiicient thatthe hooks 30 and the latching bars 32 provide suflicient force to resistthe foam pressure of the resin. In fact, the hook members 3G and thelatching bars 32 may be so constructed and arranged as to leave a slightgap 58 between the cover 54 and the end and side boards 26 and 28,enabling the cover 54 to be fitted and latched with extreme facility.

The fast gelation time of the resin 52 enables the rising resin enteringinto the gap 58 to gel sufficiently rapidly as to form a seal betweenthe cover 54 and the end and side boards 26 and 28, respectively, toretain the resin 52 within the mold. The core member 56 aids in forcingthe rising foam upwards and outwards to fill all the details of the mold40.

As pointed out above, a quantity of resin is preferably utilized whichis somewhat greater than that necessary to fill the cavity under freerise conditions. Hence, a positive pressure is built up by the risingresin which forms a breakdown of the cell structure at the surfaces ofthe resin and results in a generally non-porous skin being formedintegrally with the remainder of the resin retaining its porous orcelluular structure. The thickness of the skin is not large, but isapproximately on the order of A and, rather than being discreet, blendsinwardly into the porous center. The skin or surface portions of theresin casting or article are, accordingly, of greater density than theinteriors thereof, are capable of accurately filling all details of themold 40 and provide for substantial strength and scratch and impactresistance. In fact, the skin exhibits the feel and general optical andacoustic characteristics of wood.

The resin, accordingly, is permitted to rise within the closed molduntil it attains a semi-rigid state, which, with the example resin issufficiently flexible to be readily and easily removed from the mold 40.Such removal may be accomplished in many ways and may, for example, byapplying high pressure air to the air inlets 50 to bulge the bottom ofthe mold 40 generally upwardly away from the mold board 48, as shown inFIG. 6 to thereby release the molded resin from the mold 40. The moldedresin article or replica beam 52 may then be stacked and left to fullycure which, with the exemplary resin, requires twelve to twenty-fourhours. It should be noted that the position in which the replica beam isheld during curing is important. If the beam is not stacked in aperfectly straight condition, then the beam will harden in whateverposition it is stacked. A slight deviation from absolute straightness,however, is not necessarily undesirable and may result in increasedauthenticity, duplicating the effect of a slightly warped wooden beam.

After the replica beam 52 has fully cured, the flash or material whichflowed into the gap 58 may be removed in any convenient manner, as bymeans of a shaper, jointer, saw, or, as shown in FIG. 7, by means of abandsaw. Such flash removal not only provides a flat surface to aid insecuring the replica beams to a desired surface but, additionally,removes the skin from the fastening surface and enables more easysecurement to a Wall or sealing surface with adhesives. It is to benoted that the hollow left by the core member 56 serves several usefulfunctions. Firstly, as pointed out above, the presence of the coremember 56 aids in the molding process. Secondly, as resin materials arerelatively expensive, any savings in resin material may result insubstantial cost savings. Thirdly, the presence of the hollow within thereplica beam enables the replica beam to be utilized to cover pipes,electric cables, and the like. Finally, the presence of the hollowenables the utilization of toggle or spring type clips to secure thereplica beams to a mounting surface.

After trimming, the replica beams may be readily and easily finished toprovide the proper coloration. The replica beams may be readily stainedto the proper colorations by means of a conventional urethane-oil basewoodstain 60 which may be applied to the replica wooden beams 52 in anyconvenient manner, as by passing the replica beams 52 past a pluralityof spray heads 62 to spray-apply the stain 60 thereto.

After the stain 60 has been applied to the surfaces of the replica beam52, improved coloration, including variations in color density and aburnishing of the surface to increase the color realism may beaccomplished by brushing the stained surfaces while the stain is stillwet. For example, and with reference now to FIG. 9, the replica beam 52may be moved past rotating cylindrical brushes 64, having, for example,nylon bristles approximately 4" long, followed by Wiping as by hand orby means of fabric or pile wiping rolls 66, as shown in FIG. 10.

With reference now to FIGS. 11 and 12, there is shown and illustratedapparatus, generally designated by the reference character 70,fabricated in accordance with the present invention for continuouslyproducing replica Wood panels 72. It is to be expressly understood thatwhile FIGS. l-lO relate to the production of replica wooden beams andFIGS. 11 and 12 pertain to the production of replica wood panels, woodpanels may be fabricated with the apparatus and methods of FIGS. landreplica wooden beans may be fabricated with the apparatus and methods ofFIGS. 11 and 12. Moreover, substantially any desired shape articles maybe fabricated with the apparatus and methods herein.

A mold 74 may be fabricated in any desired manner, from, for example, asilicone or urethane elastomer, as described and disclosed above andformed into a continuous belt, revolving about pulleys 76, or the like,at least one of which may be driven, as by a conventional electric motorso as to continuously move the multiple cavity mold 74 thereabout. Inpassing over the pulleys 76 each of the cavities of the mold 74 may passrelative to a nozzle or spray head 78 which sprays a thin, even coatingof resin thereover.

The resin, for example, may comprise a urethane foam system ofrelatively high density, for example, a 25 lb. per cubic foot densitywhich has a very rapid gel time. The resin 80 may be sprayed from thespray head 78 in a thin, generally even coating over the molds 74 andthe replica panels 72 may be formed either individually, that is, withthe resin being sprayed intermittently or continuously with the flashbetween adjacent panels being removed in a later step. Similarly, thespray head 78 may spray continuously the full width of the mold 74 ormay be constructed and arranged for oscillating or other type movementover a pattern which will entirely fill the mold cavities.

For example, the panels 72 maybe formed continuously, as indicated inFIGS. 11 and 12.

The length and speed of the conveyor molds 74 may be selected so that,with the resin selected, the resin will be cured, at least to aself-supporting condition before reaching the pulleys or rollers 76 atthe end of the apparatus 70 spaced apart from the spray head 78.Accordingly, upon flexing of the mold 74 as it passes over the pulleysor rollers 76, the generally rigid replica panels 72 will continue tomove in a straight line, as indicated in FIG. 11 and, accordingly, willbe automatically released from the mold 74 where they may then bestacked to finish curing, trimmed, finished, or otherwise furtherprocessed.

As heretofore pointed out, replica beams and panels may be produced inaccordance with this invention having substantially any desireddimension and may be readily cut or severed by conventional woodworkingtools to fit where required, or may be butted together to form longerassemblies. Yet further, replica beams and panels may be fabricated todimensions which are easily handled and adapted to be readily and easilyassembled in juxtaposition to represent the appearance of a single unitor assembly of greater dimension. In accordance therewith, the replicabeam or panels may be molded or fabricated to additionally represent orprovide replicas of fastening means, such as bolts, pegs, dowels, or thelike, particularly adjacent the edges or ends therewith, as wouldordinarily be utilized to secure the wooden beams with a surface or witheach other. The replica fasteners may be stained or painted to match thebeams, to contrast therewith, or to represent other materials, such asiron.

While the invention has been described, disclosed, illustrated and shownin terms of certain preferred embodiments or modifications which it hasassumed in practice, the scope of the invention should not be deemed tobe limited by the precise embodiments or modifications herein described,disclosed, illustrated or shown, such other embodiments or modificationsas may be suggested to those having the benefit of the teachings hereinbeing intended to be reserved especially as they fall within the scopeand breadth of the subjoined claims.

What is claimed is:

1. Method of molding rigid, replica Wooden beams having the feel,appearance and stain characteristics of wood comprising, the steps of,partially filling a mold disposed in a mold box with a low density rigidurethane foam resin reaction mixture, covering said mold box with acover to form a gap between said cover and said mold box to restrict therise of said foam resin to less than the free rise volume thereof tocause pore breakdown and formation of a substantially non-porous surfaceskin thereon of increased density and hardness, allowing said resin torise and seal said gap and at least partially cure within said mold todefine a rigid, relpica beam, removing said beam from said mold,removing said skin from at least a mounting portion of said replica beamto enable and enhance the mounting of said beam, applying a wood stainto said beam and burnishing the stain while still wet on said beam so asto provide the coloration, color gradients, and textures of handhewnwood to said beam.

2. Method defined in claim 1 further comprising, at least the additionalstep of, positioning a core within the mold to form the resin upwardlyand outwardly to a generally U-shaped cross-sectional configuration.

such gap by the rising resin foam. 1

References Cited UNITED STATES PATENTS 3,219,473 11/1965 Dimond 117-64 R3,246,059 4/1966 Moroni et a1. 264-54 X 2,724,642 11/1955 Brown 161-413UX 3,291,873 12/1966 Eakin 264-54 3,527,851 9/1970 Bulgin 264-176 RX3,538,207 11/1970 Toole 264-85 X 3,250,840 5/1966 Procopio 264-176 X2,210,000 8/1940 Peel 264-347 X 1,633,590 6/1927 Lamplough 264-3472,210,000 l8/l940 Peel 264-347 X 3,248,758 5/1966 Schmitz et a1. 264-219X 3,327,029 6/ 1967 Pincus et al. 264-335 X 3,446,885 5/1969 Krauss264-225 3,248,758 5/1966 Schrnitz et al. 264-219 X 3,472,809 10/1969Hardman 264-225 X 3,504,079 3/ 1970 Hall 264-225 3,525,783 8/1970Prikkel 264-225 X 3,561,181 2/1971 Bassett 52-309 3,641,228 2/ 1972Fleck 264-53 8 FOREIGN PATENTS 541,064 5/1957 Canada 106-34 574,1414/1959 Canada 117-98 F 592,489 2/1960 Canada 1l7-C.B. 687,808 6/1964Canada 264-225 705,296 3/1965 Canada 264-54 OTHER REFERENCES Moroni,Rolf and Heinz B. Schmetkamp, Novel Process for Molding Rigid UrethaneFoam," in Journal of Cellular Plastics, July 1965, pp. 406-418.

Dow Corning Bulletin, Greater Versatility in Design and Production WithSilastic RTV, Midland, Mich., Dow Corning, 1961, 8 pp.

Morse, G. T., Flexible Urethane Molds for the Furniture Industry, in SPEJournal, June 1969, vol. 25, pp. 53-55.

Saunders, I. H. and K. C. Frisch, Polyurethanes, Chemistry andTechnology, Part II Technology. New York, Interscience, 1964, 'vol. XVI,Part II, pp. 337- 341, 432-435.

PHILIP E. ANDERSON, Primary Examiner U.S. Cl. X.R.

117-64 R, 138.8 D; 161-159; 264-54, 162, 225, 331, DIG. 14; 425-4, DIG.44

